Field of the Invention
The present invention relates to an image processing apparatus, and in particular relates to an image processing technique for performing optimal tone control for each object region in an image.
Description of the Related Art
Conventionally, it is known that blown-out highlights or blocked-up shadows occur in a part of a captured image when the dynamic range of an image sensor for the captured object is insufficient. For example, in the case of capturing an image of a person outdoors against the light on a sunny day, since the luminance of the sky is far greater than that of the person, blown-out highlights occur in the entire sky region under exposure conditions suitable for the person, and blocked-up shadows occur in the person region under exposure conditions suitable for the sky.
For such a view against the lights, Japanese Patent Laid-Open No. 2009-71768 has disclosed a technique for controlling tones so as to prevent blown-out highlights and blocked-up shadows. Japanese Patent Laid-Open No. 2009-71768 suppresses blown-out highlights and blocked-up shadows by detecting a face region, and controlling brightness and tones of the face based on the brightness of the face region and its surrounding region.
However, since the technique disclosed in Japanese Patent Laid-Open No. 2009-71768 is a tone control method specific to face regions as described above, blown-out highlights or blocked-up shadows of objects other than faces (e.g., flowers, animals, or still subjects) cannot be suppressed.